Caster



Oct. 11, 1949. I I G. F. SHEPHERD 2,484,189

(EASTER Filed Aug. 28, 1945 (/40 Wm.- 4fJ/W Patented Oct. 11, 1949 rare-s PATENT crews CASTER iGeorgeiFrederick Shepherd, Brighton, Victoria, Australia Application/August 28, 1945, Serial N0. 613;138 rim-Australia July;2?6,i1fl44 IThis= inventionrelates ,to caster wheels and .has particular though 1 notspecificsreierenceito caster wheelsifor use withuarticlessof .furnituretoiprovlde freedom .of vmovement .o'f the-same -upon a .fioor or .likesuppQrtingIsurface.

Caster wheels -.,or casters of the usual .swivelling typecommonl-y used On articleseof iurniture have certainldisadvantages, mainly arising from the ,necessarily :small dimensions act the :rollers, which .sink .into and depress the surface of a carpet '.or .floor .covering and thus impede .free and smooth running \of an article of furniture. Moreover, the small rollers cause \undue wear and damage ofethe carpetor:- floorv covering, @particularly :if the article As -subjected 'lto frequent movement. 7

lf therroller be increaseddnsize to-avoid such disadvantages, thecaster. increases in 1height :to an abnormal extent and becomes unduly large and bulky. Moreover, the =distance =of the axis of the-roller from the '--vertical PiVOtaI'IaXiS Of the caster is correspondingly increased, thus augmenting the: leverage effect-of zthe weight on the roller supon-the pivotalaxisandfltending to cause binding and excessive frictional :resistance to swivelling movements, thereby adversely 'reffectingthe sensitivityof -selfalignment-cf the caster.

:In a order to iavoid these disadvantages, masters have been previously :devised in which rollers of substantially hemispherical construction were provided. Such rollers areladvantageous in that they (may ibe =.of :relatively large size without increasing .the :dimensions of -a caster 'in general.

'Casters :having hemispherical 1.0118115 :rotatably mounted :in inclined :hearings 'ofiset :from and adapted :to swivel aloout Wertical axes :have been proposed, but such irollers had disadvanta es :in that lubricant could not be -:retained in the: offset bearings. .-Moreover, :in-such previously known casters, .the hemispherical :rollers rhad an iunduly large surface contact z-particularly -upon "carpets having "ithickipiles, so much so, that J'castering movements were restrained and considerable efiort was necessary to propelarticles of furniture to which the casters were fitted.

The principal object of this invention as to provide a compact caster of hemispherical roller type and 'of heat appearance having -great mechanical='strength and free running characteristics and having,asupporting wheel or -roller of considerably greater diameter 'than the :usual roller, while eliminating "the above recited disadvantages of -casters -of usual type "or *construction.

Another object of the dnven-tion is to so arrange and construct the inclined axis about which the hemispherical roller rotates, thatthe rotating bearingsurface 'of theHatter is continu 'ousiy'lubricated-andisso-disposed'thatlubricant i2, is .retained vand does not require replenishment for long periodsoftime.

.Aifurtherobjectiisito constructthelhemispherical rollerzin such azmanner that'thefloor contact surface is reduced by the ,provision on the roller of an .outstanding peripheral -.tread or band .of relatively large diameter.

The invention will ".be better understood from the following description vof the exemplary =arrangementshownintthe accompanyingidrawingsi In-these drawings:

Figure 1 is :an elevation of a-caster suitable for attachment to an article of furniture.

v.F'igure =2 is .a sectional elevation of the caster shown in Figure 1 with a portioniremoved for clearer illustration.

:FigureB is asection on lthelline :3--/-3 .in iligure-2.

.Eigure 4 illustrates a detail of .the -invention.

In these drawings, the numeral .5 aindicates 2a fixing ,plate for .attachmentta a.:leg .or other-part of. an article of -.urniture inotlshownl, and -'I a spindle rigidly securedto theaplate 6 -andarranged to Y depend .vertically ,fromthe same.

The spindle 1 extends \vertically through an aperture .8 .in .a substantiallyhemispherical cup member 9 which is associated, as hereinafter vdescribed, withr'a-icomplementarycupmember 0, likewise of substantially hemispherical \formation, which comprises the -.supp.orting roller of the roaster (and :is provided with ,a peripheral floor-engagingpartor tread rim Iila.

.The tread :rim Jim .is [integral with the "cup member Eli-0, and the iformer comprises a :seg-

men-tahportion ofiasspheraof greater radius than thebody partof-the member Ill.

The interior of the=tread-rim 40a is recessed to .receive thermargin'al edge .of the cup-member 9, a small clearance :being provided Joetween the surfaces l of "the recess and thecup :member.

:Ituwill .beiobserved :and understood that-the cupimembers sand to when assembled, comprise a :substantially spherical shell, "which is sealed against :entry 10f dust and :dirt except :for the small clearances provided between ithe :edges 'tof the 'cupimembers and loetween the spindle :1 and aperture 5.8.

'iFhe zspindle 71 within a hole H form'eii in a. :blook 1'2, -the Zhoie 'll :beingrcylindrical to provide an upright "bearing for 'the spindle 1 and being closed at "the lower :end 5 [3 to "form a root step or=thrust bearing t0-support the weight impose'r'l upon theplate t, see Figure 2. In order to provide 'afreely movable thrust 'bearing'of low frictional resistancefthelower-end of thespindle Fispoint'ed'as 'at NL'an'd theclosed end [3 ofthe hearing hole 'I I included "angle of the "conical end of the hole ll *formed'conically, as at t5, the

being more obtuse thanthe "included angle 61 the vertical" spindle "1 I on the axle l9.

a, tapped hole I8 into which is screwed a spindle or axle 19 having a head 20 formed appropriately for spanner engagement.

The axle I9 when mounted in the lug I1 is inclined to horizontal and is spaced apart orofiset from the vertically dependent spindle'1,

and it will be apparent that 'thisidisposition of the axle I9- will be maintained in allirotative' positions of the block 12 and the lug ll about v the spindle 1, see Figures Z and 3.

, The cup member 9 is secured to the axle l9 by a "screw 2! passed" through said member into engagement with a tapped hole 22 in the head The supporting roller H] has an internal boss 23 axially bored at 24 to fit the axle [9, so that the roller I0 is journalled upon and rotates about the inclined axle I9 in passing over a floor surface. The end of the axle l9 is poin'ted and the inner end of the hole 24 is made of conicalformation similarly to 'the vertical spindle I and hole II, as" and for the purposes previously described.

Fixed to the inclined lug 11; as by screws25, is a retaining plate or member 26 which serves the dual purposes" of retaining the block 12 upon and the supporting roller For the latter purpose the plate 26 is recessed at 21 to accommodate a flange 28 on the boss 23, and said'plate is formed with a flange 29 which projects into a peripheral groove 30 on the boss 23. Accordingly, the flange 28 is retained be-' tween the lug IT and the flange 29 to prevent displacement of the boss 23 from the axle l9; The'r'ecess 27 and the groove 30 are made of somewhat greater widths than the flanges 28 and 29 to provide sufiicient clearance to ensure that end thrust is supported by the pointed end of the axle' l9.

For the purpose of preventing displacement of the block 12 from the vertical spindle 1, the latter is provided with a'peripheral collar 3| which is engaged by an overlying lug 32 formed on an extension 33 of the retaining plate 26.

'Th'ehemisp'herical supporting roller I0 and the relatively fixed hemispherical cup member 9 comprise in combination a hollow spherical shell enclosing the vertical and inclined bearings. Access to the bearings for lubrication or repair is readily obtained upon withdrawal of the screw 2|, whereupon the cap member 9, which forms a cover'of the spherical shell, may be removed. Upon 'removalof the cup member or cover 9, the screws may be taken out, thereby releasing the retaining plate 26 to set free for removal the block [2 from the spindle 1 and the roller H] from the axle l9. 1 The closed end bearings II and 24 as above described enable them to be charged with lubricant during assembly of the caster and the bearings provide a reservoir for the lubricant and self lubrication for the spindle I and axle l9.

It will be apparent that lubricant cannot escape from the hole II and the axially bored boss 23, so that-the caster will function efficiently -for long periods without replenishment of lubricant. In.use, and as a consequence of the comparatively largediameter of the supporting roller and the closeness'of its axle to the vertical swivel axis, a caster constructed as described travels 4 tracks with and follows the direction of travel of an article of furnitureto which it is, attached. Moreover, the complete enclosure of the bearings excludes dust from the same, while the provision for lubrication ensures a maximum of service. Furthermore, the provision of the rim tread or outstanding band of relatively large diameter on the hemispherical roller prevents unduly deep penetration of the roller into a carpet having a thick pile and assists the castering action.

Iclaim:

1. A caster comprising a rotatable hemispherical roller having its edge portion enlarged to form' a peripheral floor-engaging tread and a recess within said enlarged portion, a complementary hemispherical member marginallyfitting within said recess and forming, together with the rotatable hemispherical'roller, a spherical shell, said complementary hemispherical member having an aperture therein,'-an attachment member, a spindle secured to said'attachment member and extending through said apir ture, a bearing sleeve rotatably fitting said'spin dle, a lug projection'integral with the' bearing sleeve, an axle secured to said lug projection and ofiset from and inclined with respect to said spin dle, a'hollow boss on the rotatable'hemispherical roller rotatably fitting the axle, said spindle having a collar and'said-hollow bosshaving-a circumferential flange, anda retaining member dis connectably fixed to said lug projection and en gaging said-collar and flange to maintain the roller on the axle and thespindle in the bearing sleeve.

2. A caster comprising a rotatable hemispheri'-- cal roller having itsedge portion enlarged to form a peripheral floor-engaging tread anda recess within said enlarged portion, a complementary hemispherical member marginally fit} ting withinsaid recess and forming, together with'the rotatable hemispherical roller, a spherical shell, said complementary hemispherical member having an aperture therein, an attachment plate, a spindle secured to said attachment plate and extending through said aperture, a bearing sleeve rotatably fitting said spindlea lug projection integral with the bearing sleeve, anaxle secured to said lug project-ion and offset from and inclined with respect to said spindle, an axial sleeveintegral with the rotatable hemisphericalroller rotatably fitting the axle, a circumferential flange on said spindle and on said axial sleeve; and a retaining plate disconnectably fixed to said lug projection and engaging said circumferential flanges to maintain the roller on theiaxle and the spindlein the bearing sleeve.

GEORGE FREDERICK SHEPHERD.

REFERENCES crrnp The following references are of record in the file of this patent: UNITED STATES PATENTS t 1 Number Name Date 1 309,273 Whitney '.Dec. 16, 1884.- 412,308 Treat Oct. 8, 1889 1,285,142 Happensack Nov. 19, 1918 2,096,239 Geyer Oct. 19,1937 2,332,089 Knight Oct; 19,1943

FOREIGN PATEN V Number Country Date 291,663 Great Britain- June 7,1928 109,416 F rance May18, 1931 

